Bond Stress Capacity of Steel Reinforcing Bars Embedded in Graphene-Enhanced High-Performance Concrete

Abstract

Effective and reliable force transfer between steel reinforcing bars and concrete is necessary for reinforced concrete buildings to be designed as efficiently as possible. Significant reductions in load capacity and structural rigidity could be the outcome of inadequate connection between the bars and concrete. With the recent discovery of graphene, new opportunities for the development of nano-sized cementitious additives have emerged. The present study investigates the effect of graphene nanoplatelets (GnP) on the bond stress capacity of steel reinforcing bars embedded in GnP-enhanced high-performance concrete (HPC). Effects of various GnP contents and diameter and embedded length of the bar were evaluated. Bond stress-slip behaviour between the bar and concrete was examined by performing pull out tests on cylindrical samples. Findings revealed that the GnP-enhanced HPC improved the bond stress owing to the confinement and bridging effects of GnP. Addition of GnP at the concentration of 0.02 % increased the bond stress by more than 41.28, 18.9 and 53.90% for steel bars with diameters of 10, 12 and 16 mm, respectively, at the same bar embedded length. Presence of GnP reduced the initial slip of the bar owing to the improved adhesion between the bar and the surrounding concrete.